The major function of absorbent articles, such as disposable diapers and adult incontinent briefs, is to absorb and contain body exudates. One common mode of failure for such products occurs when body exudates leak out of the gaps between the article and the wearer's leg and/or waist to adjacent clothing because they are not immediately absorbed within the article. As such, contemporary absorbent articles typically contain stretchable materials in the waist, side and cuff regions to provide sustained fit and a good seal of the article to the wearer's body.
One known technique for providing such stretchable materials is the incorporation of strands, films or nonwoven fibrous webs made of elastomeric materials. Typically, such materials are stretchable in at least one, and possibly multiple, directions. However, because the films or webs are made entirely of elastomeric materials, they are relatively expensive. Furthermore, these materials tend to have more drag on skin surface, resulting in discomfort to the wearer of the article. In some selected approaches, these stretchable strands or films are laminated to one or more substrate layers, such as nonwoven webs, plastic films, or nonwoven/film composites. Since these substrates typically are made of thermoplastic materials, they have very limited stretchability and are relatively stiff. Consequently, these laminated structures provide considerable resistance to stretch and/or conformity to a wearer's geometry. This conformity deficiency is compounded by the uniformity of these laminates, thus making them unable to adapt to the varying three-dimensional nature of the wearer's anatomy.
Another known technique for providing such stretchable materials is the incorporation of stretch-bonded laminates and neck-bonded laminates. Stretch-bonded laminates are made by stretching an elastic strand in the machine direction (MD), laminating it to a nonwoven substrate while it is in the stretched state, and releasing the applied tension so that the nonwoven gathers and takes on a puckered shape. Whereas, neck-bonded laminates are made by first stretching the nonwoven substrate in the machine direction such that it necks (i.e., reduces its cross direction (CD) dimension), then bonding CD oriented elastic strands to the substrate while the substrate is still in the stretched, necked state. Thus, the neck-bonded laminate will be stretchable in the CD, at least up to the original width of the nonwoven before it was necked. In some selected approaches, a combination of stretch-bonding and neck-bonding techniques are used to deliver stretch in both MD and CD directions. In this combined approach, at least one of the components is in a tensioned (i.e., stretched) state when the components of the laminates are joined together. While this combined approach provides multi-directional stretchability, the uniformity of these combined laminates is unable to adapt to the varying three-dimensional nature of the wearer's anatomy.
Yet another known technique for providing such stretchable materials is the incorporation of zero strain stretch laminates. Zero strain stretch laminates are made by bonding an elastomer to a nonwoven while both are in an unstrained state. These laminates are then incrementally stretched to impart the stretch properties. These incrementally stretched laminates are stretchable only to the extent afforded by the non-recovered (i.e., residual) extensibility of the laminate. For example, U.S. Pat. No. 5,156,793 discloses a method for incrementally stretching an elastomer-nonwoven laminate, in a non-uniform manner, to impart elasticity to the resulting laminate. While this approach may provide non-uniform stretchability, this non-selectable stretch does not adequately adapt to the varying three-dimensional nature of the wearer's anatomy.
What is needed is an absorbent article having stretchable properties for sustained fit and conformity to the wearer's anatomy while also being adaptable to the varying three-dimensional nature of the wearer's anatomy. More specifically, said absorbent article should be properly shaped and/or sized to the wearer for better fit, comfort, and wearer appearance, yet have the ability to maintain the required tension when on a wearer to achieve sustained fit and prevent sagging and/or drooping of the article. For example, said absorbent article should provide better shaping (i.e., contouring) of the buttocks and/or waist region. In the case of a diaper, better fit and comfort can also impart better functional performance such as reduced leakage since the diaper would better conform to the shape of a wearer.